At present, video games are perhaps the best known form of computer graphics apparatus. However, the field embraces many other systems as for use in training, design, entertainment, modeling, and so on. Typically, computer graphics systems give the viewer the impression of looking through a window at a picture, somewhat like a television display.
To generate a picture, advanced computer graphics systems select content from basic forms (primitives), orient the selected forms with respect to a viewpoint, account for hidden surfaces, then process picture elements (pixels) to develop individual fragments of the display which are scanned line by line to activate the display as in a raster pattern.
Typically, primitives or objects are mathematically defined and stored in three dimensional world space in what is sometimes referred to as an environmental memory. Conventional techniques involve selecting object data from the environmental memory that is relevant to a desired scene, transforming the data representative of such objects into a convenient coordinate system for relationship to a selected viewpoint and clipping or cutting away parts of the objects that are outside the field of vision. Then the object data is scan converted and processed into an array of picture elements (pixels) that are displayed collectively to represent an image display.
Processing for individual pixels involves determining the objects to be represented in each pixel as with regard to hidden surfaces, boundaries, or object transparency. Object data may be combined, as by blending to avoid jagged lines or edges, then shaded or textured to accomplish various surface effects or patterns. Conventionally the processed pixel data is stored in a frame buffer from which it is cyclically fetched to drive a scan line raster display, as in a cathode ray tube (CRT).
Computer graphics techniques for texturing surfaces have long been well known, as to lay a pattern on a specific surface. For example, texture may be obtained by sampling a photographic image containing a desired texture and mapping the texture onto a smooth surface in a display. Such techniques are disclosed in both of the books, Principles of Interactive Computer Graphics, Second Edition, Newman & Sproul, McGraw-Hill Book Company, 1979, and Computer Graphics--Principles and Practice, Second Edition, Foley, van Dam, Feiner, and Hughes, Addison-Wesley Publishing Company, Inc., 1990.
Generally, previous implementations of traditional texturing involve mapping a two-dimensional surface pattern onto an object. Typically the texture pattern represents a digitized texture that may be disposed on either a planar or a curved surface. In addition to texturing an object simply with a pattern, as to depict bricks, texturing techniques also have been proposed to accomplish other effects. For example, contour displays have been accomplished using texturing techniques as disclosed in U.S. Pat. No. 4,855,934, entitled System for Texturing Computer Graphics Images, granted Aug. 8, 1989, to John Robinson. Generally, the system of the present invention involves the use of two-dimensional texturing techniques to accomplish further special effects and images in computer generated displays, as movement or animation by a subject.
Computer graphics systems capable of providing dynamic displays, including animated objects, are well known and widely used. For example, such computer graphics system have been widely used in aircraft simulators for training pilots. Such graphic display systems may provide one or more window views, depicting a flight path and including moving objects. Generally, traditional techniques for accomplishing animation in such displays necessitate complex and extensive processing operations. Conventionally, such systems require a vast quantity of computation for each frame of a rapidly changing display. Accordingly, a continuing need exists for techniques and systems to simplify the generation of animated displays.
Quite independently of computer graphics animation techniques, it has been proposed to accomplish improved displays by using two-dimensional texturing techniques to depict visual images, for example, foliage on trees. In such displays, traditional techniques have processed three-dimensional graphics data to accomplish the major substance of a display then, two-dimensional texture is applied to represent details of trees. Of course, such techniques have limitations, for example substantial displacement of a viewpoint may reveal defects in the two dimensional components of the display. In any event, while such techniques have been useful traditionally, their application has been limited to represent static image components.
Generally, the system of the present invention involves the use of sequenced two-dimensional texture maps to provide an animated object in a computer graphics display. Somewhat broadly, the system involves the use of animation sequences mapped on an object somewhat in the manner of traditionally mapping texture patterns onto an object. To consider a specific example, an object might be formulated defining a transparent planar surface facing the viewpoint. A series or set of texture maps bearing an animated figure then may be mapped sequentially onto transparent objects to provide a dynamic display. In that regard, the transparent object reveals only the figure on the so-called "texture map" which is not, in fact, a traditional texture pattern, but rather is an animation sequence. Accordingly, the composite display reveals the animated figure as a dynamic image component. Such techniques afford considerable economy in processing with resultant savings of time and memory capacity and provide a method for displaying interactive figures involved in complex motion.
The system of the present invention further contemplates the utilization of specific object forms to accomplish particular results. For example, an object carrying an animated texture display may take the form of a so-called "stamp" as well known in the art, consisting of an object defining a plane that is maintained perpendicular to the line of sight from the viewpoint. An object in the form of multiple intersecting planar sheets also has been determined to afford useful animated texture displays. Furthermore, the object bearing an animated figure may be part of a dynamic coordinate system whereby further movement may be imparted to the object.
Further aspects of the present invention involve techniques for developing two-dimensional data for the creation of animation texture maps. Specifically in that regard, various techniques may include scanned data, video-based data, computer graphics generated data, and so on. Accordingly, two-dimensional data may be variously formulated, as an animation sequence of a figure, for application to a transparent display object to accomplish any of a variety of depicted figure motions within a display. By cyclically, or otherwise repeating, the application of the two-dimensional data to the object, prolonged dynamic displays can be accomplished. As a result, improved displays can be afforded with economy and efficiency. Conversely, nonrepeating sequences may be displayed to represent figure motions which are not cyclical in nature.